Muffler



INVENTOR. Jfra z(/.

lllllllllllllllllllllllllllllllllll I- III I .II I II E. G. STRAW MUFFLER Filed Feb. 5, 1965 July 4, 1967 United States Patent O ABSTRACT OF THE DISCLOSURE Close tolerances in the bushing ends of a one-piece muffier shell having a straight through gas flow tube are eliminated by pinching folds in the shell metal inwardly of the shell ends to reduce its diameter and cause it to tightly grip the ends of the gas flow tube.

This invention relates generally to exhaust systems for automotive vehicles, and more particularly, to improvements in the art of automotive mufllers.

It is a general object of the present invention to provide an improved muffler construction of an extremely simple design.

It is a more patricular object of the present invention to provide an improved mufiler construction comprising a central gas flow tube or conduit and means formed on the mufiier shell or housing extending around the central gas flow tube for rigidly supporting the gas flow tube therewithin.

It is yet another object of the present invention to provide an improved muflier construction of the above character that is easy to assemble and which may be manufactured with a minimum of close tolerance requirements.

It is still a more particular object of the present invention to provide an improved mufller construction of the above character wherein the external shell or housing is necked down or swaged radially inwardly at its opposite ends to support the gas flow tube therewithin.

Other objects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a longitudinal side elevational view, partially broken away, of a preferred form of the muffler construction of the present invention;

FIGURE 2 is a transverse cross-sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is a tranverse cross-sectional view taken along the line 33 of FIGURE 1;

FIGURE 4 is a fragmentary longitudinal cross-sectional view of an alternate form of the muffler construction of the present invention; and

FIGURE 5 is a transverse cross-sectional view taken along the line 55 of FIGURE 4.

Referring now to FIGURES 1 through 3 of the drawing, a mufller construction 10, in accordance with a preferred form of the present invention, is shown as comprising a hollow cylindrical external shell or housing 12 and an elongated gas flow tube or conduit 14 which extends coaxially within the housing 12. A plurality or bank of substantially fine flat louvers, generally designated 16, are formed around the tube 14 to provide a predetermined area of communication between the interior of the tube 14 and the annular chamber defined between the inner periphery of the housing 12 and the exterior of the tube 14.

As best seen in FIGURES 1 and 2, the opposite ends of the shell or housing 12, are formed with reduced diameter inlet and outlet bushings, generally designated 18 and 20, which respectively comprise cylindrical outermost sections 22 and 24 which are adapted to be secured 3,329,237 Patented July '4, 1967 in a conventional manner to the adjacent ends of an associated exhaust pipe and tailpipe (not shown). The bushings 18 and- 20 also comprise innermost sections 26 and 28, respectively, that serve to support the opposite ends of the gas flow tube 14 within the housing 12, as will be described.

In accordance with the principles of the present invention, the bushings 18 and 20 are formed in the ends of the housing 12 by initially necking down or swaging the ends of the housing 12 radially inwardly to the diameter of the sections 22 and 24. This operation is preferably accomplished by means of a conventional mandrel and swaging die apparatus. After the swaging operation has been performed on the ends of the housing 12 to reduce them to. the desired inlet and outlet bushing size, the innermost sections 26 and 28 of the bushings 18 and 20 are subjected to a pinching operation which reduces the diameter of the sections 26 and 28 such that they tightly grip or engage the opposite ends of the gas flow tube 14. In particular, preferably four rectangularly shaped pinched sections, generally designated 30, are formed in each of the sections 26 and 28, the excess metal between each of the sections 30 being gathered into four U-shaped folds or pinches disposed one between each adjacent pair of pinched sections 30 and generally designated by the numeral 31. The sections 30 are formed such that the inner peripheries thereof tightly engage the outer periphery of the ends of the tube 14, whereby the sections 30, together with functioning to rigidly secure the opposite ends of the tube 14 within the mufiier housing 12, serve to provide a substantially gas-tight seal or joint between the outer periphery of the ends of the tube 14 and the inner periphery of the sections 26 and 28.

Referring now to FIGURES 4 and 5, a muffler construction 32, in accordance with a slightly modified form of the present invention, is shown as comprising an external housing or shell 34, a cylindrical inner shell 36 which is mounted coaxially within the shell 34, and a louvered gas flow tube or conduit 38 which is coaxially supported within the inner shell 36. As best seen in FIG- URE 4, the outer (right) end of the inner shell 36 is necked down or swaged radially inwardly into a reduced diameter outlet bushing 40. In a similar manner, the outer (right) end of the external shell or housing 34 is necked down or swaged radially inwardly into a reduced diameter section 42 whose inner periphery is contiguously engaged and rigidly secured, as by spotwelding or the like, to the outer periphery of the bushing 40 and thus serves to support the right end of the inner shell 36 within the mufiler construction 32.

As best seen in FIGURE 5, the inner (left) end of the reduced diameter bushing 40 is formed with a section 44 that is further reduced in diameter to securely engage or grip the end of the gas flow tube 38 in a gas-tight connection. In particular, the section 44 comprises a plurality (four) of pinched down areas 48, the excess metal adjacent each of the areas 46 being gathered into a plurality (four) of U-shaped folds or pinches, generally designated 50. This is done in substantially the same manner as described in connection with FIGURES 1 through 3; however, in this case, the U-shaped folds or pinches 50 are shown as starting on a somewhat larger diameter, as indicated at 52. As previously state, the pinched down areas 48 are in a gas-tight engagement with the outer periphery of the tube and thereby prevent exhaust gases from passing between the interior of the bushing 40 and the annulus defined between the inner periphery of the shell 36 and the outer periphery of the tube 38.

A primary feature of each of the hereinbefore described embodiments of the present invention resides in the fact that close tolerances in necking down or swaging the ends of the shells 12 and 36, are virtually eliminated, the reason for this being that the circumferentially spaced pinched down sections 30 and 48 that are formed in the ends of shells 12 and 36 subsequent to the swaging operations serve to rigidly secure the ends of the tubes 14 and 38 within the shells 12 and 36, respectively. Thus, it is unnecessary for the sections 18, 20 and 40 of the shells 12 and 36, respectively, to be swaged to a size exactly corresponding to the outer diameter of the tubes 14 and 38 supported therewithin. Accordingly, the shells 12 and 36 may be manufactured at a rapid rate and with minimum tool wear.

While it will be apparent that the embodiments of the present invention illustrated herein are well calculated to fulfill the objects above stated, it will be appreciated that the present invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. An exhaust gas muffier comprising a one-piece integral tubular shell and a perforate gas flow tube inside the shell, said shell having a main body portion of one diameter and slotted bushing portions at opposite ends of a smaller diameter than the body portion and having outer axial sections adapted to receive exhaust and tailpipe conduits whereby the shell is connected in an exhaust gas system, each bushing portion having a gas flow tube connecting portion located adjacent to and axially inwardly of the outer axial sections, the opposite ends of the gas flow tube being received in the respective gas flow tube connecting portions, each flow tube connecting portion having a plurality of radially extending circumferentially spaced U-shaped folds therein and circumferential tube clamping sections between and joining the folds and in gas tight clamping engagement with the ends of the gas flow tube, said tube clamping sections having an internal diameter less than the internal diameter of the outer axial sections of said bushing portions.

2. The method of making an exhaust gas muffler which comprises forming an elongated one-piece tubular shell having a main body portion of one uniform diameter and opposite end bushing portions of a smaller uniform diameter, said shell having a uniform diameter gas flow tube inside with opposite ends thereof located inside the axially inner portions of said end portions, and pinching U-shaped folds into the axially inner portions of said bushing portions to clamp said bushing portions tightly to the ends of the flow tube but leaving the outer axial portions thereof of the original uniform diameter.

References Cited UNITED STATES PATENTS 1,938,973 12/ 1933 Oldberg.

2,088,296 7/ 1937 Kingsley.

2,367,753 1/1945 Buck 181-35 2,541,373 2/ 1951 McLeod 18148 2,548,965 4/ 1951 Gaugler.

FOREIGN PATENTS 1,351,921 12/1963 France.

892,780 3/ 1962 Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

ROBERT S. WARD, ]R., Examiner. 

1. AN EXHAUST GAS MUFFLER COMPRISING A ONE-PIECE INTEGRAL TUBULAR SHELL AND A PERFORATE GAS FLOW TUBE INSIDE THE SHELL, SAID SHELL HAVING A MAIN BODY PORTION OF ONE DIAMETER AND SLOTTED BUSHING PORTIONS AT OPPOSITE ENDS OF A SMALLER DIAMETER THAN THE BODY PORTION AND HAVING OUTER AXIAL SECTIONS ADAPTED TO RECEIVE EXHAUST AND TAILPIPE CONDUITS WHEREBY THE SHELL IS CONNECTED IN AN EXHAUST GAS SYSTEM, EACH BUSHING PORTION HAVING A GAS FLOW TUBE CONNECTING PORTION LOCATED ADJACENT TO AND AXIALLY INWARDLY OF THE OUTER AXIAL SECTIONS, THE OPPOSITE ENDS OF THE GAS FLOW TUBE BEING RECEIVED IN THE RESPECTIVE GAS FLOW TUBE CONNECTING PORTIONS, EACH FLOW TUBE CONNECTING PORTION HAVING A PLURALITY OF RADIALLY EXTENDING CIRCUMFERENTIALLY SPACED U-SHAPED FOLDS THEREIN AND CIRCUMFERENTIAL TUBE CLAMPING SECTIONS BETWEEN AND JOINING THE FOLDS AND IN GAS TIGHT CLAMPING ENGAGEMENT WITH THE ENDS OF THE GAS FLOW TUBE, SAID TUBE CLAMPING SECTIONS HAVING AN INTERNAL DIAMETER LESS THAN THE INTERNAL DIAMETER OF THE OUTER AXIAL SECTIONS OF SAID BUSHING PORTIONS. 